In this chapter, we'll see how to implement a laundry monitor room with several sensors capable of alerting the user directly on their WhatsApp account when a specific event occurs.
We'll see how to connect a sound sensor and a light sensor to our BeagleBone Black and then how we can monitor our washing machine with them. Also, we'll see how we can interact with the user directly on the user's smartphone by using a WhatsApp account in order to notify them of some events.
Let's assume that our laundry room is equipped with a washing machine and a lamp used by the user when they have to pick up the laundry. In these conditions, the BeagleBone Black can be equipped with some special sensors to detect when the washing machine has started or finished its job and when someone goes into the laundry room to pick up the washed clothes.
In this scenario, the BeagleBone Black should detect when the washing machine has been started by the user and then wait until the job has finished. At this point, the system can generate a WhatsApp message to alert the user that they have to pick up their clothes. When the user enters into the room, the light is turned on, and when they leave the room, the light is turned off. In this manner, our BeagleBone Black can detect when the user has done their job and then restart the cycle.
As just stated, in this project we need two different kind of sensors: one to detect when the washing machine starts/stop, and one to detect when someone enters/exits the laundry room. The former task can be achieved by using a sound detector, that is, a device that is able to measure the environment sound level; while the latter task can be achieved by using a light sensor, that is, a device that is able to measure the environment light. Both these signals can be compared with thresholds in order to detect our relevant events.
When the washing machine is running, we should measure a high sound level for a long amount of time; while it is not running, the environment sound should be near to zero for a long time. On the other hand, we can assume that the person designed to pick up the washed clothes has to turn the light on in the laundry room, while the light is normally turned off when there is nobody in the room.
This time, to implement the software of this prototype, we can use a state-machine with the following states and their relative transactions:
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State |
Description |
Actions |
Transaction conditions |
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Idle state; the washing machine is not working. |
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Sound detected! Keep monitoring the environment for a while. |
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Continuous sound detected so the washing machine has started its job. |
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No more sound detected! Keep monitoring the environment for a while. |
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No more sound for a long delay; the washing machine has finished... |
